Narrowband UVB has a greater immunosuppressive systemic effect as compared to broadband UVB. Specifically, narrowband UVB causes significant depletion of Langerhans cells, and this may decrease the cutaneous cellular immune response to topical allergens such as DNCB. As narrowband UVB penetrates skin more deeply, we postulate that the therapeutic effectiveness of ultraviolet B light is related to direct modulation of leukocyte activation and apoptosis in lesional skin. The most sensitive test of altered immune function is evaluation of cytokine release which will be done. To futher investigate the mechanism of action of narrowband UVB phototherapy specifically by studying immunological markers in the blood and tissue as well as apoptosis in circulating T-lymphocytes. In addition, we want to evaluate the ability of NB-UVB and BB-UVB to modulate a cutaneous DTH response to a recall antigen.